Polacanthus (Many Spikes)
Polacanthus (Many Spikes)
Named By : Richard Owen - 1865
Diet : Carnivore
Size : Estimated 4 – 5 meters long
Type of Dinosaur : Armoured Dinosaur
Type Species : Herbivore
Found in : United Kingdom, Isle of Wight, Sussex
When it Lived : Early Cretaceous, 125 million years ago
Polacanthus is an early ankylosaurian dinosaur that ate plants and was spiked, armoured, and protected. Its name comes from the Ancient Greek polys/polus- “many”, and akantha/akantha- “thorn” or ‘prickle”.
Although there are many species in the genus Polacanthus, only Polacanthus foxii has been recognized as valid.
Polacanthus was either a quadrupedal ornithischian or a “bird-hipped dinosaur”. It lived in western Europe 130-125 million years ago. Polacanthus foxii was named in honor of a 1865 discovery on the Isle of Wight. This creature is not well-known, as there are few fossils. Its head was often depicted in early drawings. This is because it was only known from its rear half. It reached a length of approximately 5m (16 ft). It was covered in spikes and armour plates. It could have been a member of the Nodosauridae’s basal family.
Polacanthus was an average-sized ankylosaur. Gregory S. Paul in 2010 estimated the length of Polacanthus at 5m (16 ft) and its weight at 2 tons (2.2 short tons). Thomas Holtz provided a lower estimate of 4m (13ft), and 227-454kg (500-1.000 lbs), in 2012. The ankylosaur’s hindlimbs are quite long, especially considering the length of its right femur.
In 2011 Barrett e.a. Two possible autapomorphies were identified by Barrett e.a. A 2020 study found one autapomorphy in the ischia: their ends curve toward each other at half their length, with their inner edges touching.
The armour configuration was restored by the subsequent descriptionrs. Hulke knew that Polacanthus had a large, “pelvic shield” (or “sacral defense”) made of a fused sheet or a layer of dermal bone. This was possibly attached to the underlying bone but decorated with tubercles. This feature is also shared by other “polacanthine,” (basal nodosaurids), dinosaurs like Gastonia and Mymoorapelta. This shield measures 108 cm wide by 90 cm long when combined with the holotype. It has four rows of horizontal rows of larger, keeled osteoderms on each side. They are surrounded by smaller ossicles.
These are often fused together to create flat armor plates. Hulke believed that there were two rows per side of keeled bone osteoderms on the tail. Hulke assumed that the spikes, which were found along with the fossil’s remains, had been attached to the rump. Nopcsa suggested a different arrangement. Nopcsa believed that the tail and front of the body, including the neck, had two parallel rows of spikes. One per side. Each row on the front body would have been made up of five spikes. He claimed that seven of these were preserved with the fossil, five from the right and two from the left. Twenty-two pairs of shorter spikes would have been used for the tail rows. Of the fifteen that are still extant, eight were from the left and seven were from the right. Because the spikes are asymmetrical, their positions can be more or less deduced. In 1987, Blows agreed with Nopcsa. However, he also identified three types of spikes, Type A, B, and C. This allowed him to classify fossil finds that often differed from the Holotype spikes in many details. Henley Hobbs, his father and a footprint were found on the Isle of Wight in 2013. A picture of the footprint can be found inside the dinosaur farm.